Variable Rate Working Memories for Phonetic Categorization and Invariant Speech Perception

Speech can be understood at widely varying production rates. A working memory is described for short-term storage of temporal lists of input items. The working memory is a cooperative-competitive neural network that automatically adjusts its integration rate, or gain, to generate a short-term memory code for a list that is independent of item presentation rate. Such an invariant working memory model is used to simulate data of Repp (1980) concerning the changes of phonetic category boundaries as a function of their presentation rate. Thus the variability of categorical boundaries can be traced to the temporal in variance of the working memory code.Air Force Office of Scientific Research (F49620-92-J-0225, 90-0128); Defense Advanced Research Projects Agency (ONR N00014-92-J-4015); Office of Naval Research (N00014-91-J-4100

Neural Dynamics of Phonetic Trading Relations for Variable-Rate CV Syllables

The perception of CV syllables exhibits a trading relationship between voice onset time (VOT) of a consonant and duration of a vowel. Percepts of [ba] and [wa] can, for example, depend on the durations of the consonant and vowel segments, with an increase in the duration of the subsequent vowel switching the percept of the preceding consonant from [w] to [b]. A neural model, called PHONET, is proposed to account for these findings. In the model, C and V inputs are filtered by parallel auditory streams that respond preferentially to transient and sustained properties of the acoustic signal, as in vision. These streams are represented by working memories that adjust their processing rates to cope with variable acoustic input rates. More rapid transient inputs can cause greater activation of the transient stream which, in turn, can automatically gain control the processing rate in the sustained stream. An invariant percept obtains when the relative activations of C and V representations in the two streams remain uncha.nged. The trading relation may be simulated as a result of how different experimental manipulations affect this ratio. It is suggested that the brain can use duration of a subsequent vowel to make the [b]/[w] distinction because the speech code is a resonant event that emerges between working mernory activation patterns and the nodes that categorize them.Advanced Research Projects Agency (90-0083); Air Force Office of Scientific Reseearch (F19620-92-J-0225); Pacific Sierra Research Corporation (91-6075-2

A Study on Obesity and its Relationship to Socioeconomic Background and Current Earnings

With larger meal portions and fewer natural food production methods, many suggest that people find it difficult to maintain a healthy diet. Nevertheless, certain individuals have been able to maintain a high-quality nutritional status and avoid this unhealthy condition. What are the reasons for these differences between individuals in weight outcomes? Moreover, how does this unhealthy weight outcome affect an individual’s current economic situation? In this study, I will examine the effects of socioeconomic background on obesity and test whether an individual’s weight has an impact on their present salary or wage levels

The Study of Ionospheric Response to Precipitation Using Sounding Rocket Observations

Understanding the role that the ionosphere plays in phenomena such as the development of auroral arcs and ion outflow is basic to the investigation of these processes and critical to the advancement of the broader study of magnetosphere-ionosphere coupling. Sounding rockets present an optimal platform for such studies, allowing low-cost access to altitudes that are difficult to reach by other means. Additionally, these measurements are key to validating current models and furthering understanding of the near-Earth space environment. This thesis highlights two particular rocket-borne instruments that measure electron populations in the ionosphere: the Electron Retarding Potential Analyzer (ERPA) and the Electron PLASma (EPLAS) instrument. It also presents analysis of the first in situ measurements of the ionospheric feedback instability (IFI) occurring within the Alfvén resonator in the vicinity of an auroral arc, a phenomenon that may play a role in the upward acceleration of ions and contribute to upflow. Another study highlights correlations between electron temperature and density and ion upflows. Simulation results, validated by rocket observations, show that increased ionospheric density inhibits the strength of the ambipolar field considered necessary for Type-2 ion outflow. Despite this however, the simulations show that increased densities result in increased net upflow fluxes. New radar data shows that sunlight effects might play an important role in controlling upflows, as photoionization can change ionospheric densities by as much as an order of magnitude seasonally

School Victimization and Bullying Experiences: Cross-national Comparisons Between Canada and the United States

The victimization of children in school and its mental health consequences have become national problems in both Canada and the United States, with evidence that severe cases of peer victimization might precede and/or be related to posttraumatic stress disorder. This study examines the frequency of victimization in schools, perpetrated by both peers and educators, and the psychological outcomes. The cross-national study included 1007 college/university students from four universities in the US and 210 university students from mid-western Canada. The “Student Alienation and Trauma Scale–Revised” (SATS–R) measures students’ negative experiences in school and assesses whether an individual developed PTSD. Overall, Canadian students remembered more victimization in school than US students. For both country samples, the verbal/relational bullying factor was most often identified as a student’s very worst school experience (approximately 40% for both countries). Both samples had similar rates of PTSD after their very worst school experience with no real differences in the types of symptoms experienced by students after their very worst school experience

Understanding the Costs and Benefits of Deepwater Oil Drilling Regulation

The purpose of this paper is to provide a conceptual framework for understanding how analysis of costs and benefits might be incorporated into an assessment of regulatory policies affecting deepwater drilling. We begin by providing a framework for analyzing the life-cycle impacts of oil drilling and its alternatives, including onshore drilling and importing oil from abroad. We then provide background estimates of the different sources of oil supplied in the United States, look at how other oil supply sources might respond to regulations on deepwater drilling, and consider the economic costs of these regulations. After providing a comprehensive description of the potential costs and benefits from various types of drilling—including, when possible, estimates of the magnitude of these benefits and costs—we discuss the extent to which these costs and benefits may already be taken into account (or reinforced) through the legal, regulatory, and tax systems and through market mechanisms. We conclude by presenting a framework and simple example of how a cost–benefit analysis might be used to inform regulation of deepwater drilling, and sum up the policy implications of our work.catastrophic oil spill, cost-benefit analysis, government regulation, liability